Handling of received implicit null packets

ABSTRACT

A router includes a network ingress processor and a network egress processor. The network ingress processor is configured for modifying a received MPLS packet such that an internal header thereof includes a pre-configured IP flow identifier therein in place of an as-received MPLS flow identifier. Such modifying is performed in response to the network ingress processor parsing a MPLS label stack of the received MPLS packet to determine if an existing MPLS label of the label stack needs to be replaced with an Implicit Null label and in response to determining that there is no other label in the MPLS label stack. The network egress processor includes a flow selector configured for directing packets dependent upon a type of flow identifier included in an internal header thereof, for receiving the modified MPLS packet, and for replacing the internal header with a port-specific header.

FIELD OF THE DISCLOSURE

The disclosures made herein relate generally to distributed routerarchitectures and, more particularly, to processing of MultiprotocolLabel Switching (MPLS) packets that require implicit null handling in adistributed router architecture.

BACKGROUND

Multi-Protocol Label Switching (MPLS) is a packet-forwarding technologythat uses labels to make data forwarding decisions. Each MPLS label isdefined by a particular MPLS label value. MPLS labels having an MPLSlabel value of 3 are of particular importance to the discussions herein.More specifically, a MPLS label having a MPLS label value of 3 is a MPLSImplicit NULL label.

In an MPLS router, processing of an incoming implicit NULL packet (i.e.,a packet having a MPLS label value of 3) requires updating differentLayer 2 headers before transmitting the packet out of the router basedon what is carried as the Layer 2 payload. Typical implementation in thedistributed architecture of a router requires parsing the packet twice,first on ingress processing module and second on egress processingmodule.

Existing systems use separate hardware assist or a Field ProgrammableGate Array (FPGA) module to perform update of the Layer 2 header. SuchLayer 2 header update is performed by re-parsing the packet in theegress direction. However, hardware implementation is costly.Alternately, in a network processor based implementation, an egresspacket parsing module can be implemented to update the Layer 2 headerappropriately. However, this still incurs extra expense in the form ofusing extra packet parsing cycles in the network processor, therebylowering the overall performance of the router.

Therefore, handling of received Implicit Null packets in a manner thatprecludes the need for re-parsing of such packets in the egressdirection would be advantageous, desirable and useful.

SUMMARY OF THE DISCLOSURE

In a network of routers having a distributed architecture, differentnetwork processors of a router are used for ingress and egressprocessing of a common packet. Embodiments of the present inventioneliminate extra processing cycles of such processors by precluding theneed to parse packets in the egress direction (i.e., parsing by thenetwork egress processor). In accordance with embodiments of the presentinvention, to process the MPLS packet that requires implicit NULL packethandling, only the ingress network processor parses such packets. Morespecifically, if an MPLS label is being swapped with an implicit NULLlabel, a check is performed by a network ingress processor of a routerto determine if there are any other labels in the MPLS stack. If theMPLS label being swapped is the last label in the MPLS label stack, theinternal header of the packet is modified to include a new flowidentifier. For example, the internal header is replaced with aninternal header having an Internet Protocol (IP) flow identifier (i.e.,a flow identifier that identifies the packet as needed to be forwardedfrom a router via IP communication standard). A flow selector of anegress router identifier is pre-configured for causing the networkegress processor to append a different Layer 2 header (i.e.,port-specific Layer 2 header) onto the packet, therefore avoiding theneed to reparse the MPLS packet at the network egress processor.

In one embodiment of the present invention, a method comprises aplurality of operations. A network ingress processor performs anoperation for parsing an MPLS label stack of a received MPLS packet todetermine if an existing MPLS label of a MPLS label stack of thereceived MPLS packet needs to be replaced with an Implicit Null label.The network ingress processor performs an operation for removing theexisting MPLS label and checking to determine if there is any other MPLSlabel in the MPLS label stack. Such removing and checking are performedin response to the network ingress processor determining thatreplacement of the existing MPLS label of the existing MPLS label withthe Implicit Null label is required. The network ingress processorperforms an operation for providing the received packet with an internalheader including a pre-configured IP flow identifier and thereaftersending the packet to a network egress processor in response to thenetwork ingress processor determining that there is no other MPLS labelin the MPLS label stack. A flow selecting portion of the network egressprocessor performs an operation for selecting routing parameters for thepacket in response to the network egress processor receiving the packetand recognizing the pre-configured IP flow identifier. The networkegress processor performs an operation for providing the received MPLSpacket with an updated Layer 2 header configured dependent upon at leastone physical network parameter related to network infrastructure overwhich the packet is transmitted from the network egress processor.

In another embodiment of the present invention, a network has aplurality of routers distributed therein. A first one of the routersincludes a network ingress processor configured for modifying a receivedMPLS packet such that an internal header thereof includes apre-configured IP flow identifier therein in place of an as-receivedMPLS flow identifier. Such modifying is performed in response to thenetwork ingress processor parsing a MPLS label stack of the receivedMPLS packet to determine if an existing MPLS label of the label stackneeds to be replaced with an Implicit Null label and in response todetermining that there is no other label in the MPLS label stack. Asecond one of the routers includes a network egress processor having aflow selector configured for directing packets dependent upon a type offlow identifier included in an internal header of a packet and forreplacing the internal header with a port-specific Layer 2 header inresponse to determining that the modified MPLS packet includes thepre-configured IP flow identifier within its internal header.

In another embodiment of the present invention, a routing apparatuscomprising a network ingress processor and a network egress processor.The network ingress processor is configured for modifying a receivedMPLS packet such that an internal header thereof includes apre-configured IP flow identifier therein in place of an as-receivedMPLS flow identifier. Such modifying is performed in response to thenetwork ingress processor parsing the MPLS label stack of the receivedMPLS packet to determine if an existing MPLS label of the label stackneeds to be replaced with an Implicit Null label and in response todetermining that there is no other label in the MPLS label stack. Thenetwork egress processor has a flow selector configured for directingpackets dependent upon a type of flow identifier included in an internalheader of a packet and for replacing the internal header with aport-specific Layer 2 header in response to determining that themodified MPLS packet includes the pre-configured IP flow identifierwithin its internal header.

In another embodiment of the present invention, a routing apparatuscomprises a network ingress processor configured for modifying areceived MPLS packet such that an internal header thereof includes apre-configured IP flow identifier therein in place of an as-receivedMPLS flow identifier. Such modifying is performed in response to thenetwork ingress processor parsing a MPLS label stack of the receivedMPLS packet to determine if an existing MPLS label of the label stackneeds to be replaced with an Implicit Null label and in response todetermining that there is no other label in the MPLS label stack.

In another embodiment of the present invention, a routing apparatuscomprises a network egress processor having a flow selector configuredfor directing packets dependent upon a type of flow identifier includedin an internal header of a packet and for replacing the internal headerwith a port-specific Layer 2 header in response to determining that themodified MPLS packet includes a pre-configured IP flow identifier withinits internal header. The pre-configured IP flow identifier is in placeof an as-received MPLS flow identifier of the packet.

Any MPLS router supporting implicit NULL label processing and usingdistributed ingress and egress architecture may benefit throughincorporation of routers (i.e., routing apparatuses) configured inaccordance with the present invention. Alternatively, invention to avoidextra circuitry, it is disclosed herein that hardware-basedimplementation can also be configured in accordance with the present.

These and other objects, embodiments, advantages and/or distinctions ofthe present invention will become readily apparent upon further reviewof the following specification, associated drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a method configured in accordance with an embodiment of thepresent invention.

FIG. 2 shows a router configured in accordance with an embodiment of thepresent invention.

FIG. 3 shows a network of routers configured in accordance with anembodiment of the present invention.

FIG. 4 show a diagrammatic flow representation of an implicit nullpacket handling process configured in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

Referring now to FIG. 1, a method 100 configured in accordance with anembodiment of the present invention for handling received Implicit Nullpackets is shown. The method 100 can be practiced by a router having adistributed architecture whereby such a distributed architecture reliesupon different network processors of a router being used for ingress andegress processing of a common packet. Advantageously, the method 100eliminates extra processing cycles of such processors by precluding theneed to parse packets in the egress direction (i.e., parsing by thenetwork egress processor). To this end, the method 100 processes MPLSpackets that require implicit NULL packet handling in such a manner thatonly the network ingress processor parses the packet.

The method 100 begins with an operation 102 being performed forconfiguring a network ingress processor of a router and an operation 104being performed for configuring a network egress processor of a router(e.g., the network processors being of a same or different router). Itis disclosed herein that, in a typical deployment of routers in anetwork, all of the routers will have their network ingress processorand network egress processor configured in accordance with the presentinvention (e.g., as disclosed below).

Configuration of the network ingress processor includes providinginformation (e.g., instructions and parameters) for causing analternative header to be used instead of the original header to beplaced in front of the packet if a packet required Implicit null labelswapping and a MPLS label at the top of the MPLS label stack is the lastlabel in the stack (i.e., the MPLS swap label). The original headercontains a MPLS flow identifier and the alternative header contains apre-configured IP flow identifier (i.e., a flow identifier having knownand intended packet routing parameters). For example, the IP flowidentifier is assigned an integer of 100 and the MPLS flow identifier isassigned an integer of 101 such that IP and MPLS traffic flows areuniquely identifiable. Configuration of the network egress processorincludes the network egress processor being programmed with twodifferent flow selecting portions. A first flow selecting portion isconfigured to forward IP packets (i.e., IP flow selector) and a secondflow selecting portion is configured to forward MPLS packets (i.e., MPLSflow selector). The two different flow selecting portions can each be adiscrete flow selector or can be different portions of a common flowselector (e.g., a flow selector module).

The IP flow selecting portion is configured to append a Layer 2 headerto an IP packet (i.e., packet having IP payload) based on the physicalmedium used for transmitting such IP packet. For example, if an IPpacket is traversing through Ethernet port, the IP flow selectingportion adds an Ethernet header specifying IP as a payload. If the IPpacket is traversing through PPP/MLPPP ports, the IP flow selectingportion adds a PPP header specifying IP as a payload. Similarly, theMPLS flow selecting portion is configured to append a Layer 2 header toa MPLS packet based on the physical medium used for transmitting suchMPLS packet. For example, if a MPLS packet is traversing through anEthernet port, the MPLS flow selecting portion adds an Ethernet headerspecifying MPLS as a payload. If the MPLS packet is traversing throughPPP/MLPPP ports, the MPLS flow selecting portion adds a PPP headerspecifying MPLS as a payload.

In the case where implicit NULL swap is performed for a MPLS packet andthere are no more MPLS labels in the MPLS label stack, the packet isprovided (e.g., sent, transmitted or the like) to the IP flow selectorconfigured on the network egress processor. For all other cases, theMPLS packet is sent to MPLS flow selector configured on the networkegress processor. A network administrator using a suitable utility orapplication (e.g., that of a network management system) can perform suchconfiguration.

It is disclosed herein that the first and second flow selectors can berespective portions of a single flow selector module. It is alsodisclosed herein that such configuring can be performed for a networkingress processor and a network egress processor of each router in anetwork. Accordingly, a network ingress processor of a first routerconfigured in such a manner will be able to forward (i.e., route)packets in conjunction with a network egress processor of the firstrouter or a network egress processor of another router so configured anda network egress processor of the first router will be able to forward(i.e., route) packets in conjunction with the network ingress processorof first router or a network ingress processor of another router soconfigured.

After the ingress and network egress' processor are appropriatelyconfigured, the network ingress processor performs an operation 106 forparsing an MPLS label stack of a received MPLS packet to determine if anexisting MPLS label of a MPLS label stack of the received MPLS packetneeds to be replaced with an Implicit Null label. In response to thenetwork ingress processor performing an operation 108 for determiningwhether replacement of the existing MPLS label of the existing MPLSlabel with an Implicit Null label is required. If it is determined thatsuch replacement is not necessary, the method 100 ends and processing ofthe packet continues with a different method (e.g., in accordance withprior art packet processing). If it is determined that such replacementis necessary, the network ingress processor performs an operation 110for removing the existing MPLS label that is being swapped (i.e., labelon top of MPLS label stack) and then performs an operation 112 fordetermining if there is any other MPLS label in the MPLS label stack(i.e., the last label in the MPLS label stack). For example, a MPLSlabel is the last of the MPLS label stack if such label has a Bottom ofStack Bit set (i.e., also known as S-bit, see section 2.1 of Request ForComments (RFC) no. 3032 (i.e., RFC3032) entitled “MPLS Label StackEncoding”). Such a last label can be visualized as innermost label inthe MPLS label stack.

If it is determined that the MPLS label is not the last label in theMPLS label stack, the method 100 ends and processing of the packetcontinues with a different method (e.g., in accordance with prior artpacket processing). In the case where such replacement is necessary andit is determined that there is not any other MPLS label in the MPLSlabel stack, the network ingress processor performs an operation 114 forproviding the received packet with an internal header including apre-configured IP flow identifier (i.e., IP-specific header) andthereafter performs an operation 116 for sending the packet to thenetwork egress processor. The pre-configured flow identifier identifiesthe packet as requiring egress forwarding (i.e., transmission) via IPcommunication standard. In one embodiment, providing the received packetwith the internal header including the pre-configured IP flow identifierincludes appending a new header on the packet. In another embodiment,providing the received packet with the internal header including thepre-configured IP flow identifier includes modifying an existing header.Accordingly, it is disclosed herein that the present invention in notunnecessarily limited to such providing being carried out in onespecific manner.

After the network egress processor performs an operation 118 forreceiving the packet, an IP flow selecting portion of the network egressprocessor performs an operation 120 for determining (e.g., selecting)configuration of a Layer 2 header to be appended to the packet. A Layer2 header is one example of a type of header than can be configured andappended/provided by a method in accordance with the present invention.In view of the IP-specific header provided by the network ingressprocessor, the packet is directed to the IP flow selecting portion ofthe network egress processor as opposed to the MPLS flow selectingportion of the network egress processor. More specifically, the IP flowselecting portion of the network egress processor is configured (e.g.,programmed) to recognize the IP flow identifier, thereby causing the IPflow selecting portion of the network egress processor to process thepacket. After determining the configuration of the Layer 2 header, thenetwork egress processor performs an operation 122 for providing thepacket with a Layer 2 header whose configuration was determined at theoperation 120 above. The Layer 2 header provided to the packet isconfigured dependent upon one or more physical network parametersrelated to network infrastructure over which the packet is transmittedfrom the network egress processor (e.g., a physical network parametersuch as a type of port). In one embodiment, such providing can includeappending an updated header to the packet. In another embodiment, suchproviding can include replacing an internal header of the packet with anupdated header.

As such, it can be seen that the method 100 precludes the need for thenetwork egress processor to reparse the packet. Specifically, this isbecause the IP flow identifier and IP flow selecting portion of thenetwork egress processor are jointly configured for processing only IPpackets. Accordingly, there is no need to reparse a packet at thenetwork egress processor to determine whether a protocol of the packetis IP or MPLS. In other words, only the network ingress processor of arouter receiving the packet parses the packet (i.e., received MPLSpacket) and thereafter chooses to associate the IP flow identifier orthe MPLS flow identifier with the packet. In view of the configurationof the flow selecting portion(s) of the network egress processor at arouter that will be forwarding the packet, the network egress processordoes not need to reparse the packet to determine whether a protocol ofthe packet is IP or MPLS.

FIG. 2 shows a router 200 configured in accordance with the presentinvention. The router 200 includes a network ingress processor 205 and anetwork egress processor 210, which are jointly configured for carryingout Implicit Null packet handing functionality in accordance with thepresent invention (e.g., in accordance with the method 100 disclosedabove). The network ingress processor 205 is configured for modifying areceived MPLS packet such that an internal header thereof includes apre-configured IP flow identifier therein in place of an as-receivedMPLS flow identifier. Such modifying is performed in response to thenetwork ingress processor parsing a MPLS label stack of the receivedMPLS packet to determine if an existing MPLS label of the label stackneeds to be replaced with an Implicit Null label and in response todetermining that there is no other label in the MPLS label stack. Thenetwork egress processor 210 is configured for directing packetsdependent upon a type of flow identifier included in an internal headerof a packet, for receiving the modified MPLS packet (i.e., as modifiedby the network ingress processor), and for replacing the internal headerwith a port-specific Layer 2 header in response to determining that themodified MPLS packet includes the pre-configured IP flow identifierwithin a header thereof. In one embodiment (shown), a MPLS parsingmodule 215 is configured for providing Implicit Null packet handingfunctionality in accordance with the present invention (e.g., operations106-116 of the method 100) and a flow selector 220 is configured forproviding egress packet handling functionality in accordance with thepresent invention (e.g., operations 118-124 of the method 100).

In one embodiment, a router configured in accordance with the presentinvention includes an ingress traffic interface, an egress trafficinterface, memory, and one or more data processing devices (i.e.,processors). The ingress traffic interface is configured for beingcoupled to a network node than forwards protocol data units (PDUs) suchas, for example, packets to the router. The egress traffic interface isconfigured for being coupled to a network node than receives protocoldata units (PDUs) such as, for example, packets to the router. Thememory has instructions stored thereon and accessible therefrom. The oneor more processors are configured for accessing and interpreting theinstructions thereby performing functionality defined by suchinstructions. The one or more processors are coupled to the interfacesfor enabling communication between the one or more processors andnetwork nodes connected to the interfaces. In one embodiment, theinstructions are configured for carrying out the method 100 discussedabove such that for a given packet, the router performs Implicit Nullpacket handing functionality in accordance with the present invention(e.g., operations 106-116 of the method 100) or egress packet handlingfunctionality in accordance with the present invention (e.g., operations118-124 of the method 100).

It is disclosed herein that the piece of hardware commonly referred toin the industry as a router is one example of a routing apparatus. Otherexamples of routing apparatuses can include, but are not limited to,switches, bridges, and the like. Accordingly, it is disclosed hereinthat implicit Null packet handling functionality in accordance with thepresent invention can be carried out by various types of apparatusesthat are configured for routing protocol data units (PDUs).

FIG. 3 shows a network 300 configured in accordance with the presentinvention. The network system includes a router network 305 having oneor more carrier networks 310 connected thereto. The router network 305is connected to the one or more carrier networks 310 through a pluralityof distributed architecture routers (Router A, Router B, Router N) thatare each configured in accordance with the present invention forproviding Implicit Null packet handling functionality in accordance withthe present invention (e.g., the router 200 of FIG. 2). The plurality ofrouters (Router A, Router B, Router N) are interconnected in a networkedmanner such that packets can be received from a carrier network (orother type of network) by one router (i.e., network ingress router) andforwarded to a carrier network (or other type of network) by the same oranother one of the routers (i.e., network egress router). Each one ofthe routers (Router A, Router B, Router N) are configured for providingImplicit Null packet handing functionality in accordance with thepresent invention and for providing egress packet handling functionalityin accordance with the present invention.

FIG. 4 show a diagrammatic flow representation of an implicit nullpacket handling process configured in accordance with the presentinvention. A packet (i.e., a MPLS packet) is received from a carriernetwork by a network ingress processor. A MPLS parsing module of thenetwork ingress processor parses the packet and modifies a header of thepacket to include a new flow identifier (e.g., the IP flow identifierdiscussed above). The packet is then forwarded to a network egressprocessor through a switch fabric (i.e., of a router network). A flowselector of the network egress processor recognizes the new flowidentifier and provides the packet with an updated Layer 2 header.Preferably, but not necessarily, the updated Layer 2 header is aport-specific Layer 2 header configured in accordance with a type ofport over which the packet is transmitted from the network egressprocessor.

Referring now to instructions processible by a data processing device,it will be understood from the disclosures made herein that methods,processes and/or operations adapted for carrying out Implicit Nullpacket handling functionality as disclosed herein are tangibly embodiedby computer readable medium having instructions thereon that areconfigured for carrying out such functionality. In one specificembodiment, the instructions are tangibly embodied for carrying out themethod 100 disclosed above. The instructions may be accessible by one ormore data processing devices from a memory apparatus (e.g. RAM, ROM,virtual memory, hard drive memory, etc), from an apparatus readable by adrive unit of a data processing system (e.g., a diskette, a compactdisk, a tape cartridge, etc) or both. Accordingly, embodiments ofcomputer readable medium in accordance with the present inventioninclude a compact disk, a hard drive, RAM or other type of storageapparatus that has imaged thereon a computer program (i.e.,instructions) adapted for carrying out Implicit Null packet handlingfunctionality in accordance with the present invention.

In the preceding detailed description, reference has been made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration specific embodiments in which the present inventionmay be practiced. These embodiments, and certain variants thereof, havebeen described in sufficient detail to enable those skilled in the artto practice embodiments of the present invention. It is to be understoodthat other suitable embodiments may be utilized and that logical,mechanical, chemical and electrical changes may be made withoutdeparting from the spirit or scope of such inventive disclosures. Toavoid unnecessary detail, the description omits certain informationknown to those skilled in the art. The preceding detailed descriptionis, therefore, not intended to be limited to the specific forms setforth herein, but on the contrary, it is intended to cover suchalternatives, modifications, and equivalents, as can be reasonablyincluded within the spirit and scope of the appended claims.

1. A method, comprising: a network ingress processor parsing an MPLSlabel stack of a received MPLS packet to determine if an existing MPLSlabel of a MPLS label stack of the received MPLS packet needs to bereplaced with an Implicit Null label; the network ingress processorremoving the existing MPLS label and checking to determine if there isany other MPLS label in the MPLS label stack, wherein said removing andchecking are performed in response to the network ingress processordetermining that replacement of the existing MPLS label of the existingMPLS label with the Implicit Null label is required; the network ingressprocessor providing the received packet with an internal headerincluding a pre-configured IP flow identifier and thereafter sendingsaid packet to a network egress processor in response to the networkingress processor determining that there is no other MPLS label in theMPLS label stack; a flow selecting portion of a network egress processorselecting routing parameters for said packet in response to the networkegress processor receiving said packet and recognizing thepre-configured IP flow identifier; and the network egress processorproviding the received MPLS packet with an updated Layer 2 headerconfigured dependent upon at least one physical network parameterrelated to network infrastructure over which the packet is transmittedfrom the network egress processor.
 2. The method of claim 1 wherein: thepre-configured IP flow identifier provides information needed forforwarding the received MPLS packet in accordance with IP communicationstandard and information causing a Layer 2 header configured inaccordance with a type of port over which the packet is transmitted froma routing apparatus comprising the network egress processor to beappended to the received MPLS packet; and said selecting includesdetermining that the internal header of the received MPLS packetincludes the pre-configured IP flow identifier.
 3. The method of claim2, further comprising: providing the network ingress processor withinformation defining the pre-configured IP flow identifier prior to thenetwork ingress processor performing said parsing.
 4. The method ofclaim 1, further comprising: providing the network ingress processorwith information defining the pre-configured IP flow identifier prior tothe network ingress processor performing said parsing.
 5. The method ofclaim 1 wherein said selecting includes determining that the internalheader of the received MPLS packet includes the pre-configured IP flowidentifier.
 6. The method of claim 5 wherein the updated Layer 2 headeris a Layer 2 header configured in accordance with a type of port overwhich the packet is transmitted from a routing apparatus comprising thenetwork egress processor.
 7. The method of claim 1 wherein said at leastone physical network parameter defines a type of network infrastructureover which the packet is transmitted from a routing apparatus comprisingthe network egress processor.
 8. The method of claim 1 wherein theupdated Layer 2 header is a Layer 2 header configured in accordance witha type of port over which the packet is transmitted from a routingapparatus comprising the network egress processor.
 9. A network having aplurality of distributed architecture routers therein, comprising: afirst one of said routers including a network ingress processorconfigured for modifying a received MPLS packet such that an internalheader thereof includes a pre-configured IP flow identifier therein inplace of an as-received MPLS flow identifier, wherein said modifying isperformed in response to the network ingress processor parsing a MPLSlabel stack of the received MPLS packet to determine if an existing MPLSlabel of the label stack needs to be replaced with an Implicit Nulllabel and in response to determining that there is no other label in theMPLS label stack; and a second one of said routers including a networkegress processor having a flow selector configured for directing packetsdependent upon a type of flow identifier included in an internal headerof a packet and replacing the internal header with a port-specific Layer2 header in response to determining that said modified MPLS packetincludes the pre-configured IP flow identifier within its internalheader.
 10. The network of claim 9 wherein: the pre-configured IP flowidentifier provides information needed for forwarding the received MPLSpacket in accordance with IP communication standard and informationcausing a Layer 2 header configured in accordance with a type of portover which the packet is transmitted from the second one of said routersto be appended to the received MPLS packet; and said replacing includesselecting routing parameters for said packet dependent upon thepre-configured IP flow identifier.
 11. The network of claim 10 whereinthe network ingress processor of said first router includes informationstored thereon that defines the pre-configured IP flow identifier. 12.The network of claim 9 wherein the network ingress processor of saidfirst router includes information stored thereon that defines thepre-configured IP flow identifier.
 13. The network of claim 9 whereinsaid selecting includes determining that the internal header of thereceived MPLS packet includes the pre-configured IP flow identifier. 14.The network of claim 13 wherein the port-specific Layer 2 header isconfigured in accordance with a type of port over which the packet istransmitted from the second one of said routers.
 15. A routingapparatus, comprising: a network ingress processor configured formodifying a received MPLS packet such that an internal header thereofincludes a pre-configured IP flow identifier therein in place of anas-received MPLS flow identifier, wherein said modifying is performed inresponse to the network ingress processor parsing a MPLS label stack ofthe received MPLS packet to determine if an existing MPLS label of thelabel stack needs to be replaced with an Implicit Null label and inresponse to determining that there is no other label in the MPLS labelstack; and a network egress processor having a flow selector configuredfor directing packets dependent upon a type of flow identifier includedin an internal header of a packet and for replacing the internal headerwith a port-specific Layer 2 header in response to determining that saidmodified MPLS packet includes the pre-configured IP flow identifierwithin its internal header.
 16. The routing apparatus of claim 15wherein: the pre-configured IP flow identifier provides informationneeded for forwarding the received MPLS packet in accordance with IPcommunication standard and information causing a Layer 2 headerconfigured in accordance with a type of port over which the packet istransmitted from the routing apparatus to be appended to the receivedMPLS packet; and said replacing includes selecting routing parametersfor said packet dependent upon the pre-configured IP flow identifier.17. The routing apparatus of claim 16 wherein the network ingressprocessor includes information stored thereon that defines thepre-configured IP flow identifier.
 18. The routing apparatus of claim 16wherein said selecting includes determining that the internal header ofthe received MPLS packet includes the pre-configured IP flow identifier.19. The routing apparatus of claim 19 wherein the port-specific Layer 2header is configured in accordance with a type of port over which thepacket is transmitted from the routing apparatus.
 20. The routingapparatus of claim 15 wherein the network ingress processor includesinformation stored thereon that defines the pre-configured IP flowidentifier.
 21. A routing apparatus, comprising: a network ingressprocessor configured for modifying a received MPLS packet such that aninternal header thereof includes a pre-configured IP flow identifiertherein in place of an as-received MPLS flow identifier, wherein saidmodifying is performed in response to the network ingress processorparsing a MPLS label stack of the received MPLS packet to determine ifan existing MPLS label of the label stack needs to be replaced with anImplicit Null label and in response to determining that there is noother label in the MPLS label stack.
 22. The routing apparatus of claim21 wherein the pre-configured IP flow identifier provides informationneeded for forwarding the received MPLS packet in accordance with IPcommunication standard and information causing a Layer 2 headerconfigured in accordance with a type of port over which the packet istransmitted from the routing apparatus to be appended to the receivedMPLS packet.
 23. The routing apparatus of claim 22 wherein the networkingress processor includes information stored thereon that defines thepre-configured IP flow identifier.
 24. The routing apparatus of claim 21wherein the network ingress processor includes information storedthereon that defines the pre-configured IP flow identifier.
 25. Arouting apparatus, comprising: a network egress processor having a flowselector configured for directing packets dependent upon a type of flowidentifier included in an internal header of a packet and for replacingthe internal header with a port-specific Layer 2 header in response todetermining that said modified MPLS packet includes a pre-configured IPflow identifier within its internal header, wherein the pre-configuredIP flow identifier is in place of an as-received MPLS flow identifier ofthe packet.
 26. The routing apparatus of claim 25 wherein: saidreplacing includes selecting routing parameters for said packetdependent upon the pre-configured IP flow identifier.
 27. The routingapparatus of claim 26 wherein said selecting includes determining thatthe internal header of the received MPLS packet includes thepre-configured IP flow identifier.
 28. The routing apparatus of claim 27wherein the port-specific Layer 2 header is configured in accordancewith a type of port over which the packet is transmitted from therouting apparatus.